ARM: dts: rmobile: Increase off-on delay on the SD Vcc regulator

An ADATA 16GB Industrial MLC card has so much capacitance on the Vcc
pin that the usual toggling of regulator to power the card off and on
is insufficient. When the card is calibrated into UHS SDR104 mode, it
will remain in that mode across the power cycle and subsequent attempt
to communicate with the card will fail.

The test with this card is to insert it into an SDHI slot and perform
"mmc dev 0 ; mmc dev 0", where the second "mmc dev 0" will fail.

Fix this problem by increasing the off-on delay from 0 to 20 mS.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>